Project import generated by Copybara.
PiperOrigin-RevId: 224614037
Change-Id: I14e53449d4aeccb328f86828c76b5f09dea0d4b8
diff --git a/http2/decoder/http2_structure_decoder.h b/http2/decoder/http2_structure_decoder.h
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+++ b/http2/decoder/http2_structure_decoder.h
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+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef QUICHE_HTTP2_DECODER_HTTP2_STRUCTURE_DECODER_H_
+#define QUICHE_HTTP2_DECODER_HTTP2_STRUCTURE_DECODER_H_
+
+// Http2StructureDecoder is a class for decoding the fixed size structures in
+// the HTTP/2 spec, defined in net/third_party/quiche/src/http2/http2_structures.h. This class
+// is in aid of deciding whether to keep the SlowDecode methods which I
+// (jamessynge) now think may not be worth their complexity. In particular,
+// if most transport buffers are large, so it is rare that a structure is
+// split across buffer boundaries, than the cost of buffering upon
+// those rare occurrences is small, which then simplifies the callers.
+
+#include <cstdint>
+
+#include "base/logging.h"
+#include "net/third_party/quiche/src/http2/decoder/decode_buffer.h"
+#include "net/third_party/quiche/src/http2/decoder/decode_http2_structures.h"
+#include "net/third_party/quiche/src/http2/decoder/decode_status.h"
+#include "net/third_party/quiche/src/http2/http2_structures.h"
+#include "net/third_party/quiche/src/http2/platform/api/http2_export.h"
+
+namespace http2 {
+namespace test {
+class Http2StructureDecoderPeer;
+} // namespace test
+
+class HTTP2_EXPORT_PRIVATE Http2StructureDecoder {
+ public:
+ // The caller needs to keep track of whether to call Start or Resume.
+ //
+ // Start has an optimization for the case where the DecodeBuffer holds the
+ // entire encoded structure; in that case it decodes into *out and returns
+ // true, and does NOT touch the data members of the Http2StructureDecoder
+ // instance because the caller won't be calling Resume later.
+ //
+ // However, if the DecodeBuffer is too small to hold the entire encoded
+ // structure, Start copies the available bytes into the Http2StructureDecoder
+ // instance, and returns false to indicate that it has not been able to
+ // complete the decoding.
+ //
+ template <class S>
+ bool Start(S* out, DecodeBuffer* db) {
+ static_assert(S::EncodedSize() <= sizeof buffer_, "buffer_ is too small");
+ DVLOG(2) << __func__ << "@" << this << ": db->Remaining=" << db->Remaining()
+ << "; EncodedSize=" << S::EncodedSize();
+ if (db->Remaining() >= S::EncodedSize()) {
+ DoDecode(out, db);
+ return true;
+ }
+ IncompleteStart(db, S::EncodedSize());
+ return false;
+ }
+
+ template <class S>
+ bool Resume(S* out, DecodeBuffer* db) {
+ DVLOG(2) << __func__ << "@" << this << ": offset_=" << offset_
+ << "; db->Remaining=" << db->Remaining();
+ if (ResumeFillingBuffer(db, S::EncodedSize())) {
+ // We have the whole thing now.
+ DVLOG(2) << __func__ << "@" << this << " offset_=" << offset_
+ << " Ready to decode from buffer_.";
+ DecodeBuffer buffer_db(buffer_, S::EncodedSize());
+ DoDecode(out, &buffer_db);
+ return true;
+ }
+ DCHECK_LT(offset_, S::EncodedSize());
+ return false;
+ }
+
+ // A second pair of Start and Resume, where the caller has a variable,
+ // |remaining_payload| that is both tested for sufficiency and updated
+ // during decoding. Note that the decode buffer may extend beyond the
+ // remaining payload because the buffer may include padding.
+ template <class S>
+ DecodeStatus Start(S* out, DecodeBuffer* db, uint32_t* remaining_payload) {
+ static_assert(S::EncodedSize() <= sizeof buffer_, "buffer_ is too small");
+ DVLOG(2) << __func__ << "@" << this
+ << ": *remaining_payload=" << *remaining_payload
+ << "; db->Remaining=" << db->Remaining()
+ << "; EncodedSize=" << S::EncodedSize();
+ if (db->MinLengthRemaining(*remaining_payload) >= S::EncodedSize()) {
+ DoDecode(out, db);
+ *remaining_payload -= S::EncodedSize();
+ return DecodeStatus::kDecodeDone;
+ }
+ return IncompleteStart(db, remaining_payload, S::EncodedSize());
+ }
+
+ template <class S>
+ bool Resume(S* out, DecodeBuffer* db, uint32_t* remaining_payload) {
+ DVLOG(3) << __func__ << "@" << this << ": offset_=" << offset_
+ << "; *remaining_payload=" << *remaining_payload
+ << "; db->Remaining=" << db->Remaining()
+ << "; EncodedSize=" << S::EncodedSize();
+ if (ResumeFillingBuffer(db, remaining_payload, S::EncodedSize())) {
+ // We have the whole thing now.
+ DVLOG(2) << __func__ << "@" << this << ": offset_=" << offset_
+ << "; Ready to decode from buffer_.";
+ DecodeBuffer buffer_db(buffer_, S::EncodedSize());
+ DoDecode(out, &buffer_db);
+ return true;
+ }
+ DCHECK_LT(offset_, S::EncodedSize());
+ return false;
+ }
+
+ uint32_t offset() const { return offset_; }
+
+ private:
+ friend class test::Http2StructureDecoderPeer;
+
+ uint32_t IncompleteStart(DecodeBuffer* db, uint32_t target_size);
+ DecodeStatus IncompleteStart(DecodeBuffer* db,
+ uint32_t* remaining_payload,
+ uint32_t target_size);
+
+ bool ResumeFillingBuffer(DecodeBuffer* db, uint32_t target_size);
+ bool ResumeFillingBuffer(DecodeBuffer* db,
+ uint32_t* remaining_payload,
+ uint32_t target_size);
+
+ uint32_t offset_;
+ char buffer_[Http2FrameHeader::EncodedSize()];
+};
+
+} // namespace http2
+
+#endif // QUICHE_HTTP2_DECODER_HTTP2_STRUCTURE_DECODER_H_
